Windows 10 is already being tested for smartphones, a former Microsoft employee has claimed, according to Digital Spy.

Frequent Windows leaker Nazwil Najeeb said on Twitter that the computing giant is trialling three builds of the OS for mobiles, one of which is Windows 10.

Microsoft has not released any specific details of the smartphone edition of Windows 10, but a teaser image has confirmed that it will retain the live tiles of the firm's recent mobile platforms.

Najeeb claimed that the company will distribute two updates for Windows Phone 8.1 before Windows 10 hits next year, the second of which is expected to be incremental.

Windows 10 will work across tablets, phones, computers and Xbox consoles, bringing unity to the Microsoft ecosystem.

A prototype version called Windows Technical Preview is already in circulation among PC users.